Differentiated liftoff process for ultra-shallow mask defined narrow trackwidth magnetic sensor

Abstract

A method for manufacturing a magnetic read sensor allows for the construction of a very narrow trackwidth sensor while avoiding problems related to mask liftoff and shadowing related process variations across a wafer. The process involves depositing a plurality of sensor layers and forming a first mask structure. The first mask structure has a relatively large opening that encompasses a sensor area and an area adjacent to the sensor area where a hard bias structure can be deposited. A second mask structure is formed over the first mask structure and includes a first portion that is configured to define a sensor dimension and a second portion that is over the first mask structure in the field area.

What is claimed is: 
     
       1. A method for manufacturing a magnetic read sensor, comprising:
 depositing a plurality of sensor layers; 
 forming a first mask structure over the plurality of sensor layers, the first mask structure covering a field area removed from a sensor area and having an opening that extends over the sensor area but that is larger than the sensor area; 
 forming a second mask structure over the first mask structure, the second mask structure having a first portion that covers an area configured to define a sensor dimension and having a second portion that is formed over the first mask structure in the field area removed from the sensor area; and 
 performing an ion milling to define a sensor dimension. 
 
     
     
       2. The method as in  claim 1  further comprising after performing the ion milling, performing a liftoff process remove the portions of the first structures located in the field area; and
 performing a chemical mechanical polishing. 
 
     
     
       3. The method as in  claim 2  wherein the liftoff process includes a wrinkle bake process and a NMP chemical liftoff. 
     
     
       4. The method as in  claim 2  wherein the liftoff process includes a wrinkle bake process, a NMP chemical liftoff, and cleaning with CO 2 . 
     
     
       5. The method as in  claim 1  wherein the opening in the first mask structure encompasses the sensor area and a hard bias region located adjacent to the sensor area. 
     
     
       6. The method as in  claim 5 , further comprising:
 after performing the ion milling, depositing a thin insulation layer, depositing a hard magnetic material over the thin insulation layer, and depositing a layer of material that is resistant to chemical mechanical polishing; and thereafter 
 performing a liftoff process to remove the first mask layer; and 
 performing the chemical mechanical polishing. 
 
     
     
       7. A method for manufacturing a magnetic read sensor, comprising:
 depositing a plurality of sensor layers; 
 depositing a chemical mechanical polishing (CMP) stop layer over the plurality of sensor layers; 
 forming a first mask structure directly onto the CMP stop layer, the first mask structure covering a field area removed from a sensor area and having an opening that extends over the sensor area and also over an area adjacent to the sensor area; 
 depositing a hard mask layer over the CMP stop layer and over the first mask structure; 
 forming a second mask structure, the second mask structure having a first portion that covers an area configured to define a sensor dimension and having a second portion that is formed over a portion of the first mask structure that is in the field area removed from the sensor area; 
 transferring an image of the second mask structure onto the hard mask layer; and 
 performing an ion milling. 
 
     
     
       8. The method as in  claim 7  wherein the hard mask layer comprises C, DLC, SiC, Al2O3, TaO, Ta 2 O 5  or TiN. 
     
     
       9. The method as in  claim 7  wherein the hard mask layer is a multi-layer hard mask having formed of inorganic materials. 
     
     
       10. The method as in  claim 7  wherein the second mask is formed by first depositing a second hard mask, depositing and photolithographically patterning a second photoresist layer; performing an image transferring of the second photoresist layer pattern into the second hard mask, and then further image transferring the second hard mask pattern into the hardmask through one or more reactive ion etching (RIE) processes.